Nutrient accumulation characteristics of main litchi cultivars and their relationships with soil nutrients

To understand the parameters of nutrient requirement for fruit-bearing plants of the main cultivars of litchi (Litchi chinensis Sonn.) and the relation between litchi plant nutrient and soil fertility, and supply the basic data for nutrient management of litchi.

Ten plants from ten litchi main cultivars including ‘Feizixiao’, etc, with medium to high fruit yield and approximately 15 years of age, were excavated at fruit harvest in the main production areas of South China. The biological characteristics of these plants were examined. Moreover, leaf, fruit, trunk and root samples of ten cultivars were collected to investigate the nutrient accumulation and distribution in various parts of litchi plants. The relations between tissue nutrient contents in litchi plants and soil nutrients were calculated.

The aboveground biomass of these trees ranged from 158.2 to 344.9 kg. Fruit yield per tree varied from 38.4 to 101.8 kg and accounted for 18.0%−38.1% of total biomass of the aboveground part. Litchi leaf contained the highest nitrogen (N) content, while trunk had the maximum calcium (Ca) or N content. N or potassium (K) was detected with the upmost content in epicarp, endocarp, pulp and seed, whereas Ca commonly dominated in root. Molybdenum (Mo) was undetectable in various parts in some cultivars. Based on the yield of 50 kg fruit, N, P, K, Ca and magnesium (Mg) accumulation of litchi aboveground part was 811.9, 86.4, 586.0, 792.5 and 112.8 g respectively. And 114.5 g N, 14.4 g P, 105.1 g K, 21.6 g Ca and 12.5 g Mg were taken away with 50 kg fruit harvest, which amounted for 15.8%, 18.9%, 20.2%, 3.4% and 12.6% of total N, P, K, Ca and Mg nutrients accumulated in the aboveground part of litchi, respectively. Foliar K, Ca and Mg contents had a significantly positive correlation with soil available K, Ca and Mg contents respectively (P<0.05), whereas the other forliar nutrients were not closely related to soil nutrients.

The nutrient removal by fruit harvest and pruning is the lowest nutrient addition amount to maintain soil fertility and healthy plant growth for the next year. Soil available K, Ca and Mg contents can be used to predict K, Ca and Mg contents in litchi leaves. Application of Ca, Si and Mo in litchi is recommended to be further investigated.